Proton-exchange membrane fuel cells are well known. In a PEM fuel cell, hydrogen atoms are ionized in an anode, migrate through a specialized membrane as hydrogen cations (protons), and combine with oxygen anions at a cathode to form water. Electrons from the hydrogen flow from the anode through an external circuit to the cathode, performing work in between.
Fuel cell assemblies comprise a plurality of individual fuel cells stacked together and connected in electrical series. An interconnect element electrically connects the anode and cathode of adjacent fuel cell assemblies. For ease of manufacture, it is typical to employ the interconnect element as a structural member and to apply an anode and membrane to one side and a cathode to the other side, forming what is known in the art as a “bipolar plate.” Such bipolar plates, when stacked together, cathode of one against the membrane of the next, form a fuel cell assembly. Openings through the plates near the edges form headers for inlet and exhaust of fuel and combustion gases. Other openings may be provided for alignment during assembly or for other specialized purposes.
The plates require a seal or gasket along all outer edges and around all openings to prevent leaking of reactant gases and coolant. It is known to use separate die-cut or molded rubber gaskets, installed between the plates during assembly of a fuel cell stack. However, a serious problem exists in locating the gaskets properly with respect to the openings to be sealed. A misaligned gasket can cause leaks, stack failure, and even broken bipolar plates. Further, using separate gaskets adds significantly to the overall time of stack assembly.
What is needed is a reliable method of laminating gaskets to bipolar plate prior to assembly of the plates into a fuel cell stack.
It is a principal object of the present invention to improve the reliability of assembly of a fuel cell stack.
It is a further object of the invention to reduce waste and cost in fuel cell manufacture.
It is a still further object of the invention to improve ease of assembly of a fuel cell stack.